Propeller mechanism



btAH'UH RUO Urig- M 8 Sheets-Sheet 1 15, 1950 w. J. BLANCHARD ETAL PROPELLER uscnmxsu Original Filed m. 21, 1940 Mr)??? Jim/Ma mu 3 Q N i 5 4w MUM! J MM nnn 15, 1950 w. J. BLANCHARD EI'AL Re- 23,253

PROPELLER MECHANISM Original Filed Oct. 21, 1940 8 Sheets-Sheet 2 a J czar/6'5 sf'xme/vd M W 4-901 ill/I VIII QCHHUH KUUM Aug. 15, 1950 w. J. BLANCHARD Err-Al.

mom-2m uncmxsu 8 Sheets-Sheet 3 Original Filed Oct. 21, 1940 one Ciel-'75s Me Nezl 1950 w. J. BLANCHARD EI'AL Re. 23,253

PROPELLER MECHANISM 8 Sheets-Sheet 4 Original Filed Oct. 21, 1940 Qwuwwhom. Mr'fier JEIdna/Fara 42:4 (Jan Es 6'. J me/Vez/ am #62 M W 1-- f M U U K H b n H 1950 w. J. BLANCHARD ETAL 23,253

PROPELLER MECHANISM Original Filed Oct. 21, 1940 8 Sheets-Sheet 5 3 YW Mm Werner .ffilamelari and Czar/e: 5 .[Mae/Vf/ Liam?! HUMP-1 Aug. 15, 1950 w. J. BLANCHARD ETAL 23,253

PROPELLER macmmsu Original Filld Oct. 21, 1940 8 Sheets-Sheet 6 559 358 Ciar/es 5.1 Nae/K917 -rmufl HUUW! g- 1950 w. J. BLANCHARD ETAL Re. 23,253

PROPELLER MECHANISM Criginal filed Oct. 21, 1940 8 Sheets-Sheet 7 Men 7e? .Bzrciara' and 3' 13 Char/es s. .[Me/Vr? A118. 1950 w. .J. BLANCHARD ETAL Re. 23,253

PROPELLER MECHANISM 8 Sheets-Sheet 8 Original Filed Oct. 21, 1940 d y Z H AW 5 W W a H X S w w. n 2. Nu W RX C 3 q T 3 t n V Wu J a: J n m 3; iiuf||ll 1| 5 w w D0 T L n a w IL L Fni, fir? Z? Reiasued Aug. 15, 1950 ocAHL i-i ROOM UNITED STATES PATENT OFFICE PROPELLER MECHANISM Original No. 2,362,444, dated November 14, 1944,

Serial No. 362,072, October 21, 1940. Application for reissue October 26, 1949, Serial No.

23 Claims.

Matter enclosed in heavy brackets I: appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue This invention relates to propellers and more particularly to propellers of the tandem or dual rotation type.

It is the principal object of the invention to provide a propeller comprising two groups of propeller blades mounted coaxially and driven oppositely to each other in which provision is made for adjusting the pitch angle setting of both groups of blades as desired.

It is a further object to provide a propeller of this character in which the pitch of the two sets of blades may be adjusted with a predetermined difierential setting with respect to each other such as to provide for the utilization by the rear propeller of energy in the slip stream from the forward propeller to develop a maximum over-all output and efliciency.

It is also an object to provide such a propeller in which separate sources of power are provided for effecting adjustment of the pitch of each of the sets of propeller blades and arranged for proper concurrent control, either manually or automatically.

It is a further object to provide a separate source of hydraulic operating power for adjusting the pitch of each of the sets of blades dispensing with the use of fluid pressure transmitting connections between relatively movable parts.

It is a still further object to provide a dual rotation propeller assembly in which each of the propellers has its own hydraulic adjusting mechanism and in which one of the propellers is independently controlled and the other controlled dependently in accordance with the position occcupied by the first so that the two propellers at all times occupy proper relative positions.

It is a further object to provide a dual rotation propeller of this character in which each of the propellers is substantially balanced within the normal flight range so that the pitch of the blades tends to remain in a predetermined operative position in the event of failure of the adjusting or control mechanism.

It is a still further object to provide a dual rotation hydraulically adjustable propeller assembly in which the pitch of both sets of propeller blades is easily and rapidly adjustable over a wide range of blade angles and into a feathered position.

Other objects and advantages will be apparent from the following description, the accompanying drawings, and the appended claims.

In the drawings:

Fig. 1 is a general assembly view oi the dual rotation propeller in accordance with this inven- 2 tion, certain of the parts being shown in elevation and others being sectioned to more clearly show the construction thereof.

Fig. 2 is a transverse sectional view on the line 2-2 of Fig. 1, showing the hydraulic mechanism of the rear hub.

Fig. 3 is a detail sectional view on the line 3-3 of Fig. 2 showing the pressure relieving mechamsm.

Fig. 4 is a detail sectional view on the line 44 of Fig. 2 showing the pump valve mechanism.

Fig. 5 is a detail sectional view on the line 5-5 of Fig. 2 showing the pump mechanism.

Fig. 6 is a detail sectional view on the line 8-6 of Fig. 2 showing the construction of the accumulator.

Fig. 7 is a detail sectional view on the line 1-1 of Fig. 2 showing the speed responsive regulating mechanism.

Fig. 8 is a transverse sectional view on the line 88 of Fig. l with certain of the parts being broken away to show the construction thereof and with the outer casing removed.

Fig. 9 is a view looking toward the regulator device in the direction of the arrows 5-9 on Fig. 2, and with the outer housing or casing of the governor springs removed.

Fig. 10 is a view partially in section and partially in elevation looking toward the face of tne blade socket and showing the manner in which the fluid pressure connections are made thereto.

Fig. 11 is a sectional view through the blade socket on the line lI-ll of Fig. 10.

Fig. 12 is a transverse sectional view showing the adjusting mechanism on the line |2l2 of Fig. 1.

Fig. 13 is a sectional view on the line Iii-l3 of Fig. 12 further showing the construction of the adjusting mechanism.

Fig. 14 is a detail sectional view on the line l4l4 of Fig. 12.

Fig. 15 is a detail sectional view on the line l5-l5 of Fig. 13.

Fig. 16 is a transverse sectional view on the line Iii-l6 of Fig. 1 showing the hydraulic mechanism of the forward hub.

Fig. 1'7 is a view partially in section and partially in elevation with the casing removed from the forward hub.

Fig. 18 is a front elevational view of the forward hub with a part thereof being broken away to show the operating mechanism for securing the follow-up action.

Fig. 19 is a detailed plan view showing the removable cam plate which provides for changing the position of response of the forward hub with respect to the rear hub.

Fig. 20 is a partial detail view showing the manner in which the adjustment of the setting of the regulator valve in the forward hub is secured.

Fig. 21 is a schematic representation of the principles of control as present in this invention.

Figs. 22-24 are diagrammatic representations illustrative of the manner in which the regulation of the pitch setting of the forward hub is obtained.

Fig. 25 is an elevational view on a smaller scale of the assembled dual rotation hub.

The invention relates to a dual rotation adjustable pitch propeller, that is one in which suitable drive mechanism is provided for operating a forward hub in one direction and a rear hub at the same speed but in the opposite direction. The blades carried by the respective hubs are of opposite pitch so that the thrust produced by both sets of blades takes place in the same direction. The two sets of blades are mounted in tandem, and are arranged coaxially and relatively close together, ordinarily spaced apart a distance less than the radius of the blade, as shown for example in Fig. 25. It is found that such an arrangement results in balanced reaction forces and in substantially increased emciencies particularly under high speed conditions and with high pitch settings of the blades.

In accordance with the present invention, the pitch angles of the blades of both sets are adapted to be adjusted or varied in order to secure the best results under all conditions of operation. Provision is made for regulation of the assembly to a constant speed condition under varying flight conditions, and for the preselection of a desired speed to be maintained within the operating range of speeds, manually or under the control of instruments. The blades may be operated and adjusted over a wide range of pitch settings varying from small angles, or from a position of negative pitch if desired, up to high operating angles and into a fully feathered position. Both sets of blades are concurrently adjustable either to the same pitch or to a pitch such that there is a predetermined differential in the setting of the two blades as found most desirable and such adjustments are effected positively and rapidly. Furthermore each hub assembly is complete in itself, each incorporating its own hydraulic system, including pressure developing, controlling, and applying mechanism. Thus there are no running joints between relatively rotating parts through which fluid operating pressure is required to be transmitted under pressure, and a highly satisfactory construction and operation are thus secured.

The invention may be utilized in conjunction with various types of adjusting mechanism for varying the pitch of the blades, and is not limited to any particular arrangement for this purpose. It is particularly adapted however for use in conjunction with the propeller mechanism shown in applicants co-pending applications Serial Nos. 279,530 and 279,531 filed June 16, 1939, now U. S. Patents 2,307,101 and 2,307,102. For purposes of illustration, the invention will be hereinafter described as embodied in a propeller constructed generally in accordance with said copending applications.

Referring to the drawings which disclose a preferred embodiment of the invention, there is shown an engine housing II) from which there extends an inner drive shaft H and an outer concentric drive shaft l2. Suitable transmission mechanism is provided for driving these two shafts in opposite directions and at the same speed, such mechanism not forming a part of the present invention and not being shown in the drawings.

The rear or inner hub indicated generally at 14 has a plurality of blade sockets l5 associated therewith in which are mounted the propeller blades [5. As shown the hub comprises three such sockets and a corresponding number of blades, it being understood that any number of blades and blade sockets may be provided desired. The drive shaft l2 and hub 14 are provided with cooperating spline parts which provide for receiving and removing the hub in proper driving relation over the shaft. It is held in place thereon by a wedge ring 2| adapted to work against a tapered ring 22 at the inner end of the shaft. A lock ring 23 provides for retaining the ring 2| and the hub in assembled position.

The drive shaft 12 terminates within the confines of hub I4, while shaft I l extends forwardly and receives thereon the outer or forward hub 25. This hub is similarly provided with a number of blade sockets 25 shown as being the same number as provided for the rear hub, in which are mounted the several blades 21. The hub 25 and drive shaft II have cooperating spline portions 28 which provide for removably receiving the hub in operating position over the drive shaft. It is held in place by means of wedge ring 30 working against a tapered ring 3| which is backed by a nut 32 fastened upon the drive shaft. Wedge ring 30 is retained in place by the forwardly projecting sleeve 35 in accordance with the usual propeller construction. A looking pin 36 prevents relative rotation between the sleeve 35 and the drive shaft II, and snap ring 31 received in a groove in hub 25 provides an abutment to facilitate removal of the hub from the shaft. A sheet metal housing section 38 is preferably provided over the forward nose of the propeller to minimize wind resistance and to enclose the end of the hollow drive shaft. It will be noted that the inner drive shaft II is hollow, and offers no obstruction to the mounting of cannon or the like for firing through the hollow drive shaft.

In order to afford proper support for the forwardly extending drive shaft II, there is provided a roller bearing 40 having an inner race 4| carried by the shaft II and held in place by nut 32 and an outer race 42 in supporting contact with the forwardly projecting portion 43 of the inner hub M. In this way proper alignment and support for the two rotating shafts is provided.

A substantial part of the mechanism for securing adjustment of the setting of the blades is the same in the two hubs, and accordingly attention will be directed to the rear or inner hub, the construction of which will be described first, and thereafter the differences in construction in the forward hub will be described.

Referring to Figs 1 through 14, the construction in the inner hub comprises a radially extending plate or casting 50 which is carried by and rotatable with hub l4, being removably held in place thereon by a locking ring 5| threadedly engaged upon the hub. Attached to the outer periphery of plate 50 by means of bolts 52 is a casing or housing member 53 which together with the plate 50 forms a reservoir for receiving a quantity of pressure operating fluid.

A stationary member 55 extends into the housing, being bolted by means of bolts 56 to an adapter plate 51 connected to the engine casing or to some suitable non-rotating part. It is formed with an axially extending sleeve part 58 located immediately outwardly of sleeve 5| and extending adj acent plate 50, and projecting radially outwardly thereof it is formed with a cam member 58. The joints or points of running contact of the reservoir and this stationary member are sealed to prevent loss of fluid. For this purpose a. washer 60 is provided, which is held in place against the adjacent surfaces of plate 50 and sleeve 58 by compression spring 6|, the whole being retained by a plate 62 bolted to the inner surface of member 50 by means of bolts 63. At the point of contact of the casing 53 with the stationary member 55, a similar sealing joint indicated generally at 84 is provided, thus assuring the maintenance of an effectively sealed reservoir for containing the operating fluid.

It is found at times that under operating conditions and the normally resultant increase in temperature, air which may have leaked into the reservoir is subject to expansion and may produce a pressure increase in the reservoir. To relieve such pressure increase, the reservoir at a radially inner point thereof is provided with a pressure release in the form of a ball check valve 60 resiliently urged toward seating position by means of spring 61. Escape of air under pressure is permitted through this valve, but fluid will not escape because under conditions of operation the fluid is located at the radially outer portion of the reservoir and hence exerts no pressure as such upon the relief valve. Upon cooling, should the pressure within the reservoir fall below atmospheric, air may seep into the same through the sealed joints above described to equalize the pressure.

Within the reservoir there is located a selfcontained pressure developing and controlling system so that fluid pressure is not required to be transmitted from a stationary or non-rotating part of the propeller into the hub, and hence no packed joints operating under high pressure conditions are required. Pump mechanism is located within the housing preferably comprising a pair of pressure developing pumps. These pumps are shown at I0, and as illustrated in Fig. 2, are suitably spaced from each other arcuately so that they will function in predetermined timed relation to each other. Each pump has its own associated valve mechanism II, and there is also associated therewith a common relief valve mechanism indicated generally at 12.

Referring now to the pump mechanism, as shown in Fig. 5, the pump is mounted within the plate 50, a suitable elongated chamber I5 being integrally formed in the plate to reecive the pump. The pump piston 80 is mounted for sliding movement in a direction parallel with the axis of rotation within cylinder 8|. It carries at its outer end a cross-shaft 02 having arms 83 projecting therefrom which are guided in slots 84 formed within the outer end of the cylinder 8|. This construction provides for reciprocating movement of the piston, preventing angular or twisting motion thereof. A compression spring 86 normally urges the pump piston outwardly of the cylinder, and into such position that roller 81, carried upon the cross-shaft 82, runs in continuous bearing engagement with fixed cam 50.

The cam is preferably provided with two lobes or high points, such that upon operation of the hub and with the pump being carried around, the pump piston is forced inwardly on its pressure stroke by the high points on the cam and alternately pressed outwardly on its suction stroke by the spring 88. Provision is made for read? removal and replacement of the spring by means of a movable cap 88 threaded into the housing portion I5 and having a shank 89 thereon for guiding spring 88 thereover, the spring thus beini easily replaceable.

The pressure chamber 90 of the pump communicates directly by passage 90a with the intermediate chamber of the valve mechanism II. This mechanism as shown in Fig. 4 also is mounted within the plate 50, and comprises a suction inlet valve 92 mounted upon a central guide pin 03 and resiliently urged toward closed seating position by means of spring 84. The inlet port is shown at 95 in direct communication with the reservoir and being located radially outwardly thereof so that it will be assured of receiving a supply of the fluid from the reservoir during operation. If desired a suitable protection device may be located over the inlet to prevent impurities passing into the fluid system.

An outlet or discharge valve 96 is mounted upon the guide pin 93 and resiliently urged toward seating position by spring 91. It controls the discharge from the pump chamber 0| to the discharge chamber 98.

As will be apparent from the above, the operation of the pump and valve mechanism is as follows. Upon the rotation of the hub and plate 50, the pump is carried around with respect to cam 59, thus causing the pump piston to be alternately moved inward and outward with respect to its cylinder. Upon outward movement the pressure in the valve chamber 8| is reduced, thereby closing valve member 96 and causing valve member 92 to open to draw fluid thereinto. Upon the return or pressure stroke of the pump, valve member 92 closes because of the excess of pressure within the pump chamber, and valve 85 opens to provide for discharge of the fluid into the pressure or discharge chamber 58. Preferably a connection in the form of tube 99 is provided between the two pressure chambers so that the pressure will at all times be substantially equalized therebetween, the two pumps operating in timed sequence with respect to each other by reason of their relative location with respect to the high points on the cams.

When a suflicient operating pressure has been developed to aflord proper operation, it is no longer necessary that the pump mechanism continue to supply fluid under pressure, and its continued operation would merely result in unnecessary working and heating of the fluid. In order to relieve the action under such circumstances, the relief valve 12 is provided. As shown, this valve is also mounted within the plate 50, and comprises a movable piston member I00 having a land |0I thereon and a second land I02 of greater diameter. The piston is movable within a cylinder I03 having proper internal diameter to receive the two lands therein. The cylinder is ported at I04 in the range of land IN and a connection I05 leads thereinto from the valve chamber 9|. A second port I06 in the range of land I02 is provided and connection I01 leads thereinto from the discharge chamber 50. The interior of the valve I00 may be hollow as shown and is preferably apertured at its outer end as shown at I08 in order to permit free inflow and outflow of the fluid therefrom as the valve moves. Also stop plates I09 and III) are provided at the inner and outer limits respectively of the travel of the valve, plate III] being removably held in place to permit of ready removal and replacement of the valve.

The operation Of ths mechanism is as follows. In the position shown in Fig. 3, land IIII covers port H14 and hence the pump pressure from chamber BI is not effective. However the tube I01 is opened to the space between lands IOI and I02, and the pressure of chamber 98 is therefore effective therein. Because of the difference in the projected areas of the lands, there is a resultant force established tending to cause movement of the valve member radially inwardly. The valve body itself is subject to, centrifugal force, and its weight is suitably selected to be responsive to a predetermined speed condition. As the pump continues to operate, the pressure within the discharge chamber 98 builds up, and if not required for use, reaches a maximum desired value. At this point, the force acting upon the valve body I!) is sufficient to overcome the effect of centrifugal force thereon and results in initiating movement of the valve body radially inwardly. As soon however as the valvebegins to move inwardly, the centrifugal force effective thereon decreases because of its lesser radial distance from the axis of rotation. As a result the valve quickly is moved into its innermost position, and in such position the land IIlI uncovers the port H14 and permits fluid to flow therethrough from pump chamber 9| directly back to the reservoir. Thus while the pump continues to operate, it merely circulates the fluid substantially without pressure and hence performs only a very small and unobjectionable amount of work.

The pressure within the discharge chamber 98 is maintained meanwhile by reason of the closing of valve member 96 which thus functions as a check valve to retain the pressure in the system. Should operating fluid be required, or upon such leakage taking place as to reduce the pressure within chamber 98, the pressure effective upon the differential area of valve IOII becomes less than that necessary to retain it in its inner position. At this time it begins to move outwardly, and since the centrifugal force increases with its greater radial distance from the axis of rotation, it immediately moves to its outermost position, completely closing relief port I04, and providing for the continued delivery of pressure fluid to the discharge chamber 98.

It will thus be seen that the operation of the valve is unstable, and that it necessarily adopts one or the other of its two extreme positions. It will also be noted that inasmuch as the valve body is subjected to greater centrifugal force at higher speeds, it will automatically provide for building up and maintaining a greater pressure within the discharge chamber 98 at higher speed conditions. The actual speeds at which the valve will function are suitably selected by varying the weight of the valve, and it will be seen that it can be readily removed and replaced by a valve of different weight as required. Further the degree of pressure drop which will result in the outward movement of the valve body may be regulated by changing the relative diameters of lands "II and I02, and by varying the degree of radial movement of the valve.

In order to provide for delivery of the pressure fluid from discharge chamber 98, a pair of tubes III are provided which communicate with that chamber and are located in the body of plate 50, being preferably cast to form an integral unit therewith. These tubes lead arcuately around the drive shaft and into communication by parts IIG with a plurality of accumulators indicated generally at Il1. As shown in detail in Fig. 6, the accumulators are mounted within the plate 50 and comprise a cylinder IIB within which there is slidably mounted a piston I I9. Tube I I5 communicates with the piston so that fluid pressure is made eflective thereupon. This pressure is opposed by means of compression spring I20 acting on the opposite side of the piston, a suitable stop plate I2I being provided to limit the inner movement of the piston. In operation, the pistons are maintained in a partially depressed condition by reason of the development and maintenance of the fluid pressure transmitted thereto by tubes H5. They provide a storage space of substantial capacity in the aggregate and thus tend to reduce fluctuation in the pressure within the tube, providing more uniform pressure conditions for use. It will also be appreciated that they afford a source of pressure for return delivery to the valve chamber to replace such leakage as may occur therein, and hence increase the periods between successive operations of the relief valve and pump mechanism as described above. As shown three of the accumulators III are provided in communication with each of the tubes H5.

The pressure tube II5, as shown in Figs. '1 and 8, leads into the central part of a regulator valve chamber I25 carried on plate 50. The regulator valve body is shown at I26 and comprises lands I21, I28 and I2! spaced from each other by a portion of reduced diameter. Land I21 controls an outlet port I30 while land I28 controls outlet port I3I. A pressure operating line I32 communicates with port I30 and a pressure operating line I33 communicates with port l3I, line I32 being located radially inwardly of line I33. Pressure relief ports lma open through the chamber I25 between the lands I28 and I29, and communicate with the reservoir. The valve body is also provided with a pin I35 at its radially outer end and in the land I23 to which is attached an operating yoke I36 having threadedly received therein a lever arm I31.

Valve body I26 is mounted radially and is directly subject to the action of centrifugal force, acting upon the body itself. In order to overcome the tendency of centrifugal force to move the body outwardly, a pair of springs I40 are located within the reservoir, attached at one end to suitable fixed points such as the pump housings 10, and connecting at their opposite ends to a cross-arm I4I. Suitable stationary guides I42 are provided to maintain the springs in proper position under the flexing action to which they are subjected. Cross-arm MI is attached to lever I31 and hence a. constant opposing force is applied to the valve body for resisting the outward movement thereof.

In order to provide for variation in the response of the regulator valve, a variable fulcrum is provided for the lever I31. For this purpose a stud I45 is fastened to the valve casing, and projects therefrom generally parallel with lever I31. A shoe I46 is slidably adjustable along stud I45 and carries a roller I41 which rides upon the lever I31, forming a fulcrum therefor. It will be apparent that upon movement of roller I41, the effect of the spring force as opposing the cenbtAHCH ROOM trifugal force acting on the valve body will be varied, since any change in the position of the fulcrum roller will produce a greater proportion of change in the lever arm of the spring than in the lever arm effective with respect to the valve body. As will be more completely described hereinafter, movement of the roller toward the valve body results in lessening the spring force effective upon the same, thus causing the valve body to move outwardly to cause the application of fluid pressure in such direction as to bring about an increase in the pitch angle of the blades. The speed then tends to slow down. and the centrifugal force effective upon the valve body to oppose that of the spring is likewise reduced so that an equilibrium or balance point is established at a slower speed of rotation. The converse is equally true, movement of the fulcrum roller away from the valve body effecting an increase in the effect of the spring force and hence resulting in inward movement of the valve to cause application of fluid pressure to effect a lower pitch setting of the blades. of operation, which in turn produces an increased centrifugal force in order to again reach a balanced condition of regulation at a new speed level.

It will likewise be clear that movement of the roller toward the valve body sufllciently to bring the line of action of the spring force directly toward the roller, or to the right thereof as viewed in Fi '7, will result in the valve moving to and remaining in its outer position thus bringing about the maximum increase in the pitch of the blades. This will provide for the adiustment of the blades to a fully feathered position, where desired.

In order to effect variation in the positioning of the shoe I46 as desired during flight conditions, 2. control mechanism is provided which is accessible for operation from the aircraft. As shown, a lever arm I50 is arranged to be rockably mounted on sleeve II carried by the adapter plate 51 or other suitable stationary part, and to be actuated either manually or under the control of suitable instruments. The lever carries at its lower end a toothed sector I58 which engages with the pinion I54 of a gear and pinion assembly rotatably mounted upon a stud shaft I55 and suitablv journaled in the motor casing. The gear I56 meshes with a ring gear I51 mounted for rotation upon a stationary sleeve I58 projecting from the engine casing, the gear being suitably held therein by means of a plate I59 and snap ring I60. Meshing with ring gear I51 are a series of operating pinions I6I, shown as comprisin three pinions, each mounted for rotation in a bracket I62 carried by the adapter plate 51. The pinions I6I are symmetrically located alon the periphery of the shaft and provide for rotating shafts I63 which extend through the easing, being provided with suitable sealing means I64. Each shaft I63 is provided with a tongue and groove connection I65 with a second shaft I66 which is rotatably mounted within the stationary member 55, the tongue and groove construction providing for the ready separation of the two shaft sections from each other during assembly or disassembly of the device as hub I4 is removed or replaced upon shaft I2. Shaft I66 extends through member 55 and into the interior of the reservoir. At the point where it passes through the wall of member 55, it is formed with a shoulder I68, and in order to provide for taking up axial thrust, a notched plate There is a consequent greater speed I69 is bolted to the face of member 55 as shown at I10. The outer face of plate 55 and the inner face of plate I69 thus serve to confine the shoulder I68 and to prevent axial movement thereof, these parts thus taking axial thrust in either direction.

The forwardly projecting end of shaft I66 18 threaded as shown in I1 I and is received within a ring sleeve I12. The sleeve is splined as shown at I13 to the stationary sleeve 5| in such man ner that upon the rotation of the three shafts I66, the sleeve is caused to move axially, while being restrained against circular movement. As will be apparent, this axial movement of sleeve I12 takes place in accordance with the adjusting movement of lever I50.

A pair of levers I15 are mounted within reservoir, conveniently through the provision of lugs I16 extending upwardly from the housings of the accumulators and forming a pivot for its respective lever. Each lever carries at its upper end a shoe I11 which is adapted to ride within the peripheral groove I18 of ring I12. At their lower ends they are formed with an open-ended yoke I18 adapted to engage pins I which are fastened to the shoe I46. Thus upon axial movement of ring I12 the levers I15 are rocked upon their pivots. The shoe I46 is engaged at its opposite sides and is caused to move toward or away from the regulator valve to vary the effective force of the spring, and the length of the lever arms as previously described.

It will thus be apparent that with a fixed setting of the fulcrum roller I41 the regulator will tend to maintain a balanced position such as to bring about constant speed operation; and upon the superimposing of a manual or other control to vary the position of the fulcrum, the regulator tends to regulate to a different predetermined position.

The manner in which the pressure fluid is distributed through the tubes I32 and I33, in order to bring about respectively a decrease and an increase in the pitch setting of the blades will now be described. As shown in Fig. 8, the two tubes I32 and I33 are arranged in a generally concentric manner, each making a continuous closed circuit upon itself. Tube I32 is provided with a series of three openings I85, while tube I33 is provided with a similar series of openings I86. Each series is equidistantly arranged and the two series are arranged in staggered relation with respect to each other. These openings I and I86 project through the wall of plate 50, and are located immediately adjacent the walls of blade sockets I5. As shown in Fig. 10, a corresponding series of openings I88 is provided at the same diameter and in the same correspondin spacing as openings I85, that is, one for each of the three blade sockets. A second series I80 is provided correspondingly arranged with respect to openings I86. This provides an opening I88 and an opening I89 leading into each of the three blade sockets I5 so that pressure fluid may be supplied thereinto through the respective passages to bring about either decrease or increase in the pitch angle setting as may be desired.

As will be clear from Figs. 10 and 11, a tube I90 leads from the opening I88 into the central portion of the blade socket and a tube IBI leads from the opening I89 into a position removed from the axis of the blade. Thus fluid may be introduced through line I90 into the central portion of the blade socket and upwardly through passage I92 into the interior of a sleeve member I95. Tube IBI provides for the introduction of fluid through passages I95 and I93 to the space external of the sleeve I95 and inwardly of the actual wall of the blade root. Suitable packing I9! is provided for preventing the escape of fluid from the space external to sleeve I95 and a supply passage for the fluid is formed therethrough.

Sleeve I 95 is fastened to hub I4 by means of pins I98 so that it is mounted thereon and prevented from turning with respect thereto. At its outer end, the sleeve is provided with a packed joint 200 through which there slidably projects a hollow piston rod 20I. A piston 202 having predetermined mass is carried by the piston rod at its outer end and is arranged to operate in fluid sealed relation within a cylinder 204. The cylinder 204 is fastened to the blade I6 by means of pins 205 so that upon rotation it will effect corresponding rotation of the blade. The piston is formed with an inwardly projecting sleeve 206, the inner face of which is arranged to engage and slide over the outer face of the stationary sleeve I95. These two faces are provided with cooperating helical spline surfaces 201, so that upon radial movement of sleeves 205, it is also caused to rotate against the fixed sleeve I95. Similarly the outer surface of sleeve 206 is arranged to engage and slide over the inner surface of cylinder 204 which is suitably offset to receive the same, and these parts are provided with cooperating spiral splines 208 so that radial movement of sleeve 205 imparts additional rotational movement to cylinder 204. Thus the movement of piston 202 effects movement of its sleeve 205, and that movement causes a resultant angular or rotational movement of the cylinder 204 to take place, in accordance with the sum of the angular movements produced by the two sets of cooperating spline surfaces. The length of the cooperating spline surfaces and the pitch angles of the respective helixes are selected as desired to give the proper degree of movement for adjusting the pitch of the blades from a low or negative pitch position, through the operating range to a high pitch or feathered position. If desired the mechanism disclosed in co-pending application Serial N 0. 279,530 now Patent 2,307,101 may be utilized for this purpose.

The blade I is retained in its socket I-5 by means of a collar 2|0 threaded on to the root of the blade and engaging a series of stacked ball bearings 2 which are held within the socket by an outer threaded collar 2l2 suitably locked in place by a lock 2I3. guided for rotation upon its own axis by ball bearing 2I5, thereby providing an antifriction support for the blade upon the hub I4. In order to enclose the hub, an annular plate or casting 2I6 is bolted against the hub, providing for retaining lubricant, etc. within the same.

It will be apparent from the foregoing that introduction of pressure operating fluid into the interior of sleeve I95 through the opening I92 provides for the application of that fluid through the hollow piston rod 20I to the outer surface of piston 202. Hence such application will force the piston inwardly. The spline teeth 20! and 208 are so arranged that such inward movement of the piston produces a decrease in the pitch of the blades. Conversely when the pressure is supplied through port I3I, tube I33, openings 186, I89, and tube I9I to the outside of the sleeve I I95, it flows upwardly over the respective spline teeth 20! and 209 to effect the lubrication there- The blade is additionally of, and then into the space beneath piston 202 with resultant outward movement thereof. Upon such movement the pitch of the blades is increased. It will be understood that when pressure is applied upon one side or in one direction, the pressure is simultaneously relieved upon the other side of the piston, and the fluid in that part of the system allowed to discharge back into the reservoir by the uncovering of the corresponding port. For example when valve I 26 moves outwardly to supply pressure fluid to tube I33, land I21 moves to uncover port I30, and fluid from tube I32 is then free to flow through the open port and back into the reservoir. Each end of valve chamber I25 is open and in communication with the reservoir for return discharge of fluid from either tube.

Each blade thus has its own pressure actuating mechanism and is arranged to be operated through the positive application of hydraulic pressure in each direction to effect both pitch increase and pitch decrease. In order to maintain uniform control over the position of all the blades, each blade is provided with a beveled gear sector 220 which meshes with a ring gear 22I, suitably mounted upon ball bearing 222 carried by the forwardly projecting part 43 of hub I4. Thus gear 22l operates as a synchronizing mechanism to assure that the position of all the individual blades in the hub will be the same at all times.

As described in the above referred to application Serial No. 279,530, now Patent 2,307,101, this arrangement provides for substantially balancing the forces effective upon the blade within a predetermined position of normal flight settings. Certain forces acting upon the blade tend to cause decrease in the pitch thereof, but in the preferred arrangement these forces are not relied upon to return the blades to a lower pitch position. The weight of piston 202 is preferably chosen so that the effect of centrifugal force thereon tending to move the piston outwardly and hence to increase the pitch of the blades is substantially balanced with the forces tending to cause decrease in the pitch of the blades, at a preselected point or range within the normal operating range of blade positions. Positive application of pressure is utilized to overcome the inherent frictional forces present, and to adjust the pitch of the blades to a proper setting in both directions while provision is made for assuring the blades remaining in a satisfactory operating position even in the event of complete failure of the fluid pressure system and the control mechanism.

The mechanism in the forward hub is in many respects the same as that described above. Ex cept as otherwise indicated, the elements of structure in the forward hub similar to those of the rear hub have been given reference characters of the same order, but increased by 200. Thus, the front hub carries an annular plate 250 similar to plate 50 carried by the rear hub. This plate is retained in position on hub 25 by means of locking ring 25I threadedly received upon the hub. Bolts 252 removably attach a covering or housing member 253 to the plate 250 forming therewith a reservoir for receiving a quantity of pressure operating fluid. A sleeve member 255 is bolted to cover plate 2I5 rotatable with rear hub II and projects within the reservoir of the front hub. It is formed with an axial portion 258 and with a radially extending cam 259. Such cam however differs from the stationary cam 59 in the rear hub in that it is supported and carried by the rear hub assembly and hence is rotated in a direction opposite to that of the forward hub, producing a relative rotation between such parts of twice the individual speed. As a result, and in order to secure similar operation of the pump mechanism, earn 259 is preferably formed with only a single lobe thereon so that the same rate of pump operation will be secured. Sealing means 280 and 264 provide for enclosing the interior of the reservoir at the adjacent surfaces of plate 250 with sleeve portion 258, and at the adjacent surfaces of cover 253 with sleeve 25-5, thereby preventing escape of lubricant therefrom. Also an air pressure releasing construction similar to that shown at 66, 61 in the rear huh is preferably provided.

The reservoir within the front hub likewise contains a pair of pumps 210. arranged in spaced relation to each other, correspond ng valve chambers 21!. and a single pressure relief mechanism 212. these parts being similar in construction and mode of operation to the corresponding parts described abo e in. the rear hub.

The regulator valve body 30!! of the forward hub is slidably mounted within cylinder 30! which is carried by the plate 250. The pressure from the pressure sup ly system leads into the central port 302 and su plies pressure into the area between the two lands 303 and 304. These lands control outlets 305 and 306 respect vely and provide for establishing communication from the pressure source to operating tubes 30'! and 303 respectively. In this respect the construction is the same as previously described, the supply of pressure fluid being selectively directed to one or the other of these pressure sup ly lines, to be carried into the several blade sockets and to be there supplied to one side or the other of the individual pistons in the blade sockets to effect the adjustment of the pitch setting of the blades. It will be understood that as in the rear hub, introduction of fluid pressure through the radially inner tube 301 results in bringing about a decrease in the blade pitch while introduction through outer tube 303 causes increase in the pitch of the several blades.

However the control and operation of regulator valve 300 in the forward hub are different from that of valve I26 in the rear hub. Thus instead of being independently controlled in response to speed or manual adjustment, the regulating action of valve 330 is made dependent upon changes in the actual setting of the blades of the rear hub. By providing an element within the forward hub which is adjustable in accordance with, or in response to changes in, the setting of the blades of the rear hub, the forward regulator valve is displaced from its neutral position and made to respond to such changes in the rear blades, thereby controlling the setting of the forward blades in predetermined relation with respect thereto. A follow up mechanism is provided so that when the proper adjustment has taken place in the forward blades to correspond with the change which has occurred in the rear blades, the regulator valve will be restored to neutral position, cutting oil supply of regulating fluid to either side of the pistons. Although the valve may be arranged in a radial position for purposes of simplification and standardization of parts in the two hubs and is thus subject to centrifugal force, that force is not utilized in the control of its operation, its position being determined in the man- SEARCH ROOM ner described regardless of the centrifugal force acting thereon. For this purpose, ring gear 22! in the rear hub is provided with a forwardly extending cylindrical part (5 upon the internal face of which are provided a series of gear teeth 3|6. A shaft 3l1 is rotatably mounted within) plate 2l6 and extends therethrough with a pinion 3|! upon its overhanging end which is adapted to mesh with gear teeth 3IG. Preferably three such shafts are so positioned in uniformly spaced relation around the periphery each carrying pinion in driven relation with gear teeth 3H5, so as to secure balanced operating conditions.

Shaft 3" has a tongue and groove connection shown at 3|! with a second shaft 320 mounted within the ring 255, and extending outwardly therethrough and terminating in a threaded portion 32I within the reservoir of the forward hub. Preferably the shaft is provided with the thrust collar construction described above in connection with the shaft sections I63 and I64, providing for taking up axial thrust loads on the shaft while permitting ready separation thereof for dismantling of the hub. A grooved ring 322 is slidably mounted upon sleeve 258 and threadedly engaged by the several operating shafts 32l to be moved axially upon rotation thereof. The ring has a peripheral groove 323 within which there is adapted to ride a follower shoe 324 rotatable with the forward hub, the ring itself being rotatable with the rear hub.

It will be clear that upon any adjustment taking place in the pitch angle setting of the rear blades Ii, ring gear 22l will be correspondingly rotated, and this will in turn effect the rotation of the shaft sections 32! to effect a corresponding adjustment in the position of ring 322 and of shoes 324. Thus for every pitch angle setting of the rear propeller blades, there is a corresponding axial positioning of the shoes 324, and they respond by axial movement in one direction or the other to either increase or decrease in the pitch of the rear blades.

Referring to Figs. 17 and 18, there is shown the ring gear 330 which is mounted upon roller bearing 33f for rotation about forward hub 25. This ring gear serves the same purpose as previously described gear MI in the rear hub, in synchronizing or correlating the adjusting movements of the several blades in the forward hub, each blade having a sector meshing with the ring gear and making it necessary that all of such blades occupy the same angular position at all times. The bearing 33! is retained in place by means of a housing section 332 bolted to the forward hub as shown at 333 and with a looking ring 334 threaded into the hub 25 for retaining the same in position.

In order to provide a follow-up device responsive to the change in position of the forward blades, the ring gear 330 is provided with a forwardly extending sleeve portion 340 which is recessed as shown at 34| to provide for receiving cam plates 342 therein. The cam plates are located in spaced relation around the periphery of sleeve 340 and in symmetrical relation at either rods 346 which pass through the lower walls at either side of one of the blade sockets 25 being guided thereby for axial movement, the operating rods extending rearwardly in the zone of the throat of the blade sockets, and out of that area occupied by the pre viously described operating and adjusting mechanism. The direction of the cam tracks 344 is such that upon increase of blade pitch, rods 346 are moved forwardly or toward the forward end of the propeller, and vice versa.

Rods 346 extend through plate 250 and into the reservoir where they terminate in ball and socket joints 350. Connection is there made to floating levers 35l which extend downwardly past the opposite sides of ring 322 and are attached to the shoes 324. The two levers 35! are preferably joined together in an arcuate manner at their lower side and connection is there made to a lug 352 having an elongated slot 353 therein. A bell crank lever 355 is pivotally mounted at 356 and carries pin 351 at one end which is adapted to ride within the slot 353. At -'its other end, the lever is formed with a bifurcated part 355 which engages over pin 359, carried by the valve body 300. Thus upon pivotal movement of the bell crank lever in one direction or the other away from its neutral position, the valve body is caused to move inwardly or outwardly to provide for supply of pressure from the pressure source to the individual blade pistons for efiecting selective adjustment in the setting of the blades to effect increase or decrease of the pitch thereof.

In operation, upon a change taking place in the setting of the blades in the rear hub, a corresponding shift in the position of ring 322 takes place as described. Assuming an increase in the pitch of the rear blades to have taken place, ring 322 is moved axially toward the plate 250, i. e., toward the left as shown in Fig. 17. With rods '346 stationary, the shoes 324 move toward the forward blade sockets and lever arms 35I pivot about the point 350, causing a displacement of lug 352 and a corresponding rocking of bell crank clever 355. This movement displaces valve body 300 from its neutral position, causing it to move outwardly and supplying pressure fluid through line 359 and into the several blade pistons in the direction to cause increase of the pitch of the blades. As adjusting movement of the blades in -the forward hub takes place, ring gear 330 is caused to rotate, and the cam track 344 thus causes a displacement of rods 346 to take place to the left as shown in Fig. 17, this displacement being in such direction as to shift the pivot points 350 in the same direction as the shift imparted to ring 32!. The supply of pressure fluid to the blades in the forward hub continues therefore until such time as, with continued rotation of the blades toward increased pitch position, the pivots 350 have traveled toward plate 250 to a position in which levers 35l have returned the lug 352 to its original position. This occurs when the extent of movement of rods 346 bears the same ratio to the entire length of levers 35I that the extent of movement imparted to ring 322 and shoes 324 bears to the length of the portion of the levers inwardly of the shoes. When such conditions have been reached, valve body 300 is returned to neutral, and adjusting movement of the forward blades ceases. It will be clear that the cam 342 is made of proper shape and such as to produce the necessary extent of movement of pivots 350. Further where the lead of the .cam is uniform, the forward blades will follow in their movement the adjustments which occur in the rear blades assuming the same pitch positions throughout the entire range. In some cases it is found preferable to have a differential adjustment take place, with the pitch of the forward blades being changed in the same sense but to a greater or less degree than that of the rear blades. In such case the cam track is suitably shaped to provide whatever relation is desired between the two sets of blades throughout the entire range of adjustment thereof. For example, the pitch of the forward blades may be made to vary from that of the rear blades by a constant amount, such as a few degrees, or by a ratio, providing a greater difierential at higher blade angles. The accessibility and replaceability of the cam plate facilitates making changes in such condition as desired.

The reverse operations of course take place upon adjustment of the rear blade in the opposite direction, there being corresponding balance points for the follow-up rods 345 for every setting of ring 322 at which the valve body is restored to a neutral position.

In actual operation, these adjusting movements occur quite rapidly so that the forward blades begin to operate shortly after movement of the rear blades has begun. As soon as the valve body has been displaced from its neutral position, control fluid is supplied to the forward blades in such direction as to bring about a corresponding change and movement thereof follows immediately. In the case of an extensive adjustment of the rear blades, the movement of the forward blades takes place concurrently and with only a brief lag with respect thereto. Actual movement of the bell crank lever and the valve body therefor is relatively small, being merely enough in one direction or the other from neutral position to uncover and establish selective communication with the proper pressure supply tube.

It will be apparent from the foregoing that the forward blade adjusting mechanism will operate to maintain the blades at the predetermined pitch position corresponding to the particular setting of the rear blades. Thus assuming a change in the setting of the forward blades, for example, by reason of reduction of fluid pressure within the blade pistons, and under such operating conditions that the forces effective upon the blades would cause a reduction in the pitch thereof, such movement would rotate ring gear 330 and cause corresponding shifting of rods 346. If the change was a decrease in pitch, rods 346 would move toward the rear hub, and would pivot about shoes 324, resulting in movement of bell crank 355 and outwardly displacing valve body 300. This movement eifects introduction of pressure fluid in the direction to cause increased pitch of the blades, thus correcting for the change which presumptively occurred, the supply of fluid continuing until the pitch of the blades has been restored to its predetermined value. Analysis will show that a similar corrective action occurs upon a change in the opposite direction, the system thus effecting initial adjustment of the forward blades to a predetermined pitch position corresponding to each pitch setting of the rear blades, and then providing for maintaining the forward blades in such predetermined position.

The principle of this control has been illustrated diagrammatically in Figs. 21 through 24 in greatly simplified form in order to more clearly show the functioning and operation thereof. In this arrangement, theengine is indicated at a, the

SEARCH ROOM drive shaft for the rear hub at b and for the forward hub at bb. The rear blade socket and hub are represented at c, including all of the elements within the rectangular outline which are rotatable therewith. Similarly the forward hub, blade socket and parts rotatable therewith are shown within the left hand or forward rectangle, the blade socket being marked cc.

The manual or instrument-controlled adjusting mechanism is shown at d, effecting adjustment in the position of the slidable ring e through the toothed sector, ring gear, pinions and threaded shafts as shown. Pivotally mounted lever f rotatable with the hub carries a shoe which runs in ring e, and is rocked thereby to change the position of fulcrum roller g at its opposite end. Movement of roller g changes the effective force of spring h which is opposed to the centrifugal force acting on regulator valve bodyi.

Fluid pressure is developed by pump j, rotatable with the hub and actuated by contact with non-rotating cam k, and is supplied to the regulator valve i. Valve i controls the application of such pressure to one side or the other of the blade adjusting piston 1 within blade socket c. An abutment m and spline connection shown at 11 cause pitch adjusting movement of the individual blade upon travel of the piston 1. With lever d in any fixed position, the centrifugal force acting upon valve body i is opposed by a constant moment of force produced by spring h, and hence tends to constantly assume a position where such forces are in balance, being displaced from that position upon a departure of the speed of rotation of the propeller from the predetermined value, and upon such displacement causing a change in the pitch of the blades in the proper sense to restore such speed condition. Upon adjustment of lever d, the effect of the spring force is changed, and thus a new speed condition is selected at which the centrifugal force on the valve body will be in balance with the applied spring force, the valve being displaced from neutral to produce such change in blade pitch as will bring about such speed change.

The ring gear correlates the action of the rear blades through beveled gear sectors p carried thereby and provides for adjusting the position of ring ee in the forward hub in accordance with the setting of the blades in the rear hub through the provision of the internal teeth on ring gear 0, pinions and threaded shafts, as shown.

Pressure is developed in the forward hub by D p means 11' rotatable with the forward hub and operating against cam kk carried by the rear hub and hence rotating in the opposite direction. Such pressure is supplied to valve ii from which it may be applied to the adjusting piston 11 in the forward blade socket cc under the control of the valve. The abutment mm causes movement of piston ll to effect twisting of the blades in the forward hub through spline connection nn. Ring gear 00 actuated by sectors pp rotatable with the blades is provided with a cam plate qq having a cam groove rr therein within which there slidably operates follow-up rod ss. It terminates at point tt, where it is connected to the upper end of the lever uu, to which is connected at an intermediate point the shoes vv which ride within the ring ee. At its lower end, the point ww, the lever is connected to bell crank xx, pivotally mounted at yy 18 and having connection at point 22 with the valve body.

Fig. 22 is a diagrammatic representation of a normal or balanced position of the parts. In this position lever uu is in alignment with the one arm of bell crank lever xx and hence the bell crank occupies its neutral position and through connection zz cause valve ii to occupy its neutral position in which no fiuid is supplied to either side of the operating piston 11.

In Fig. 23, as a result of an adjustment movement having taken place in the rear hub, ring ee has moved and the shoe W is no longer in its original position, but has moved to a new position vv. Prior to movement of the forward blades, follow-up rod ss ha not moved, and hence point tt has not moved. Lever uu is therefore caused to pivot about point tt thereby causing the end ww of the bell crank to move to a position w'w', which in turn has moved the point zz to new position z'z. This results in displacement of the valve body, causing the supply of pressure fluid to one side of the piston 11. As the piston moves in response to that pressure application, the follow-up rod ss is likewise caused to move, and continues to move point tt to new position tt'. When it reaches such position t't, (shoe vv remaining at vv) the lever uu is swung to bring point ww back to the original ww position, thus restoring the bell crank xx to its original or neutral position. With the bell crank thus restored to its original position, point zz has been restored, and the valve body has been returned to its neutral position where further supply of pressure fluid is cut off. The pitch of the forward blades is thus maintained at all times in close correlation with that of the rear blades.

It is believed that this will make clear the manner of operation of the device, it being clear that upon an opposite movement of the blades within the rear hub, the opposite sequence of operations takes place in the forward hub, the position of the blades of the forward hub thus being made to follow and be dependent upon those of the rear hub. As described above, the pitch angle settings of the forward blades may be made to follow and correspond precisely with those of the rear blade, or to increase or decrease more rapidly than those of the rear hub where a differential setting of the pitch of the two blades is desired. This is accomplished through the arrangement and contour of the cam member qq and slot Tr which member may be readily changed and replaced to secure variation in the operating conditions.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. A dual rotation propeller of the character described adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs respectively associated in driven relation with said drive shafts and each provided with a plurality of blade sockets, propeller blades adjustably mounted in each of said sockets, the.

blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said sprockets for effecting adjustment of said blades to vary the pitch thereof,

separate fluid pressure developing means in each hub to supply fluid under pressure to said actuating means within that hub, and means Within each hub for controlling the application of the fluid pressure to the associated actuating means to effect adjustment of the pitch setting of the blades thereof the controlling means within one hub acting in response to changes in actual setting of the blades of the other hub.

2. A dual rotation propeller of the character described adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs respectively associated in driven relation with said drive shafts and each provided with a plurality of blade sockets, propeller blades adjustably mounted in each of said sockets, the blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said sockets for effecting adjustment of adjustment of the pitch setting of the blades,

thereof, and means for coordinating the setting of the blades of one hub with the setting of the blades of the other hub.

3. A dual rotation propeller of the character described adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs respectively associated in driven relation with said drive shafts and each provided with a plurality of blade sockets, propeller blades adjustably mounted in each of said sockets, the blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said sockets for effecting adjustment of said blades to vary the pitch thereof, separate fluid pressure developing means in each hub to supply fluid under pressure to said actuating means within that hub, means within each hub for controlling the application of the fluid pressure to the associated actuating means to effect adjustment of the pitch setting of the blades thereof, speeg r esponsive means in one of said huts for regulating the controlling means in that hub to adjust the setting of its said blades to maintain a constant speed condition, and means in the other of said hubs for effecting a corresponding adjustment in the regulation of its said controlling means.

4. A dual rotation propeller hub adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs each associated in driven relation with one of said drive shafts and having a plurality of blade sockets for adjustably receiving blades therein with the blades of one hub being of opposite pitch to those of the other, power actuated means in each hub for adjusting the pitch of the blades thereof, means in each hub for developing power to effect actuation of said power actuated means, and control means in each hub for controlling the application of said developed power to maintain a predetermined position of said blades, and means for correlating the action of the control means in said two hubs to cause both sets of blades to occupy a corresponding pitch position to each other.

5. A dual rotation propeller adapted to be driven from a pair of oppositely rotating drive shafts cmoprising a pair of hubs each associated in driven relation with one of said drive shafts and having a plurality of blade sockets, blades adjustably mounted in said blade sockets with those of one hub being of opposite pitch to those of the other, power actuated means in each hub for adjusting the pitch of the blades, means in each hub for developing power to effect actuation of said power actuated means, independent control means in one of said hubs for controlling the application of the power developing means thereof to the power actuated means thereof to effect adjustment of the pitch setting of the blades of that hrb, and eontiol means in the other said hub dependent upon the position of the blades in said first mentioned hub for controlling the application of the power developing means of said other hub to the power actuating means thereof to effect a corresponding change in the pitch setting of the blades of said other hub.

6. A dual rotation propeller adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs each associated in driven relation with one of said drive shafts and having a plurality of blade sockets, blades adjustably mounted in said blade sockets with those of one hub being of opposite pitch to those of the other, power actuated means in each hub for adjusting the pitch of the blades thereof, means in each hub for developing power to effect actuation of said power actuated means, speed responsive means for controlling the application of power developed in one of said hubs to adjust the position of the blades of that hub to maintain a predetermined speed condition, and control means associated with said other hub for controlling the application of power developed in said other hub to cause the blades of the latter hub to assume a position corresponding with those of the first mentioned hub to maintain a constant speed and balanced thrust condition of the entire propeller.

7. A dual rotation propeller adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs each associated in driven relation with one of said drive shafts and having a plurality of blade sockets, blades adjustably mounted in said blade sockets with those of one hub being of opposite pitch to those of the other, fluid pressure actuated means in each hub for adjusting the pitch of the blades thereof, a source of fluid pressure in each hub for application to said pressure actuated means to effect adjustment of the pitch of the blades, speed responsive means within one of said hubs for controlling the application of said pressure source to adjust the position of the blades of that hub to maintain a predetermined speed condition, and control means associated with the other said hub and responsive to the position of the blades in said first-mentioned hub for controlling the application of the pressure source of said other hub to the pressure actuated means thereof to cause the blades thereof to assume a position corresponding with those of said first-mentioned hub.

8. A dual rotation propeller adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs each associated in driven relation with one of said drive shafts and having a plurality of blade sockets, blades adjustably mounted in said blade sockets with those of one hub being of opposite pitch to those of the other, fluid pressure actuated means in each hub for adjusting the pitch of the blades thereof, a source of fluid pressure in each hub for application to said pressure actuated means to effect adjustment of the pitch of the blades,

speed responsive means within one of said hubs for controlling the application of said pressure source to adjust the position of the blades of that hub to maintain a predetermined speed condition, independent control means associated with said one hub for adjusting said speed responsive means to selectively vary said predetermined speed to which said propeller is regulated, and control means associated with the other said hub and responsive to the position of the blades in said first-mentioned hub for controlling the application of the pressure source of said other hub to the pressure actuated means thereof to cause the blades thereof to assume a position corresponding with those of said first-mentioned hub.

9. A dual rotation propeller adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs each associated in driven relation with one of said drive shafts and having a plurality of blade sockets, blades adjustably mounted in said blade sockets with those of one hub being of opposite pitch to those of the other, fluid pressure actuated means in each hub for positively adjusting the pitch of the blades thereof in both pitch increasing and decreasing adjustments, means in each hub for developing fluid pressure to effect actuation of said pressure actuated means, independent control means in one of said hubs for controlling the application of said fluid pressure to said pressure actuated means to adjust the blades of said hub to a predetermined pitch position, means in the other said hub dependent upon the actual position of the blades of said first mentioned hub for controlling the application of the fluid pressure within said other hub to the pressure actuated means thereof to maintain a corresponding position of the blades of that hub in relation to those of said first mentioned hub, and means for causing the pitch setting of the blades of said other hub to vary by a predetermined differential from the pitch setting of those of said first mentioned hub.

10. A dual rotation propeller adapted to be driven from a pair of oppositely rotating drive shafts comprising a pair of hubs each associated in driven relation with one of said drive shafts and havin a plurality of blade sockets, blades adjustably mounted in said blade sockets with those of one hub being of opposite pitch to those of the other, a housing associated with each hub and forming a separate closed reservoir therewith for receiving a quantity of operating fluid therein, means within each reservoir for subjecting the fluid therein to pressure to provide independent sources of pressure actuating fluid, fluid pressure actuated means in each blade socket for effecting adjustment of the pitch setting of the blades therein, control means in each hub for separately controlling the application of the fluid pressure sources thereof to said pressure actuated means, speed responsive means in one of said hubs for regulating the operation of the associated control means therein, and means in the other of said hubs and responsive to the actual setting of the blades in said first-mentioned hub for regulating the action of its said associated control means to thereby effect a corresponding pitch setting of the blades of both of said hubs.

11. A dual rotation propeller hub mechanism of the character described comprising a pair of hubs adapted to be received on oppositely rotating concentric drive shafts, blade sockets rotatable with said hubs and adapted to receive and separate fluid pressure distributing means within each hub for effecting adjustment of the pitch of the blades of that hub, housings carried by each hub and forming separate reservoirs therewith for receiving a body of pressure actuating fluid, means extending from one housing into the other housing for transmitting the adjusting of pitch of blades of one hub to the fluid pressure distributing means of the other hub, means within each hub including pump means operable upon rotation of the propeller for subjecting the respective bodies of fluid to pressure, pressure receiving means for receiving the fluid discharged from said pump means, and means for limiting the action of said pump means upon the establish ment of a predetermined pressure condition within said receiving means including valve members subject to centrifugal force upon rotation of said hubs, means for supplying fluid pressure from said receiving means to said valve means to move said valves against the action of centrifugal force when the pressure in said receiving means reaches said predetermined amount. and a by-pass associated with each said pump means and opened by movement of said valve for by-passing the fluid from said pump back to said reservoir.

12. A dual rotation propeller of the character described comprisin a pair of drive shafts rotating in opposite directions, hubs positioned on each drive shaft in tandem relation to each other, a plurality of hydraulically adjustable blades carried by each hub, a fluid-containing reservoir rotatable with each of said hubs, pump mechanism carried by each hub and communicating with said respective reservoirs, a stationary member operable upon the pump mechanism of the rear hub to provide for actuation thereof to subject the fluid in the reservoir of the rear hub to pressure, a member carried by the rear hub and operable upon the pump mechanism of the forward hub to provide for actuation thereof to subject the fluid in the reservoir of the forward hub to pressure, means within each hub for controlling the application of fluid pressure to the re spective hydraulically adjustable blades, and means responding to the changes in actual setting of the blades of one hub for initiating change in the controlling means for the other hub to effect a like change of blade setting.

[13. A dual rotation propeller of the character described which comprises a pair of hubs adapted to be received in tandem relation upon oppositely rotating drive' shafts, adjustable pitch blades mounted upon said respective hubs, fluid pressure responsive means for effecting pitch adjustment of said blades, fluid pressure means for supplying fluid under pressure to effect actuation of said pressure responsive means, independent control means for one of said hubs for controlling the supply of pressure fluid to adjust the pitch of the blades of that hub to a predetermined position, and control means for the other said h-ub dependent upon the position of the blades of said first hub for controlling the supply of pressure fluid to adjust the pitch of the blades of said other hub in substantially synchronized relation with the pitch of the blades of said first mentioned hub] [14. A dual rotation propeller of the character described which comprises a pair of hubs adapted to be received in tandem relation upon oppositely rotating drive shafts, adjustable pitch blades mounted upon said respective hubs, fluid pressure responsive means associated with each blade for effectin pitch adjustment thereof, means for synchronizing the adjusting operation of the blades of theother hub, fluid pressure means for suplying fluid under pressure to effect actuation of said pressure respc nsive means, independent control means for one of said hubs for controlling the supply of pressure fluid to adjust the pitch of the blades of that hub to a predetermined position, means for initiating the supply of pressure fluid to the pressure responsive means of said other hub in accordance with a change in the setting of the blades of said first mentioned hub, and means for terminating said supply of pressure fluid to the pressure responsive means of said other hub when the blades of said other hub have been adjusted to a position corresponding with that of said first mentioned hub.]

15. A dual rotation propeller of the character described adapted to be driven from oppositely rotating drive shafts comprising a pair of hubs adapted to be mounted in tandem relation upon said drive shafts and each provided with a plurality of blade sockets, propeller blades adjustably mounted in each of said sockets, the blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said sockets for efiecting adjustment of said blades to vary the pitch thereof, separate fluid pressure developing means in each hub to supply fluid under pressure to said actuating means within that hub, means within each hub operable from a neutral position for controlling the application of the fluid pressure to the actuating means of that hub to effect adjustment of the pitch setting of the blades thereof, speed responsive means in one of said hubs for regulating the controlling means in that hub to adjust the setting of its said blades to maintain a constant speed condition, and means in the other of said hubs for effecting actuation of said control means in said other hub away from its neutral position upon change of pitch of the blades of said first mentioned hub, and follow-up means responsive to the change of pitch of the blades of said other hub to a position corresponding to that of the blades of said first mentioned hub for restoring said control means in said other hub to'its neutral position.

16. A dual rotation propeller of the character described adapted to be driven from oppositely rotating drive shafts comprising a pair of hubs adapted to be mounted in tandem relation upon said drive shafts and each provided with a plurality of blade sockets, propeller blades adjustably mounted in each of said sockets, the blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said sockets for efl'ecting positive adjusting movement of said blades in each direction to vary the pitch thereof, separate flu'd pressure developing means in each hub to supply fluid under pressure selectively to said actuating means within that hub for effecting pitch increase or decrease, control means within each hub adjustable in each direction away from a neutral position for controlling the application of the fluid pressure 'to the associated actuating means to effect adjustment of the pitch setting of the blades thereof, speed responsive means in one of said hubs for regulating the controlling means in that hub to adjust the setting of its said blades to maintain a constant speed condition, means in the other of said hubs responsive to a change of position of the blades of said first mentioned hub for efiecting displacement of the control means of said other hub away from its neutral position in a sense corresponding to the direction of said change of position, and means for restoring the said displaced control means to neutral position when the blades of said other hub have been changed in the same sense and in a corresponding position.

17. A dual rotation propeller of the character described, adapted to be driven from oppositely rotating drive shafts comprising a pair of hubs adapted to be mounted in tandem relation upon said drive shafts and each provided with a plurality of blade sockets, propeller blades adjustably mounted in each of said sockets, the blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said sockets for effecting positive adjusting movement of said blades in each direction to vary the pitch thereof, separate fluid pressure developing means in each hub to supply fluid under pressure selectively to said actuating means within that hub for effecting pitch increase or decrease, control means within each hub adjustable in each direction away from a neutral position for controlling the application of the fluid pressure to the associated actuating means to effect adjustment of the pitch setting of the blades thereof, speed responsive means in one of said hubs for regulating the controlling means in that hub to adjust the setting of its said blades to maintain a constant speed condition, means in the other of said hubs responsive to a change of position of the blades of said first mentioned hub for effecting displacement of the control means of said other hub away from its neutral position in a sense corresponding to the direction of said change of position, means for restoring the said displaced control means to neutral position when the blades of said other hub have been changed in the same sense and to a corresponding position and removable and replaceable means associated with the control means of said other hub for predetermining the relative settings between said blades in corresponding positions.

18. A dual rotation propeller of the character described adapted to be driven from oppositely rotating drive shafts comprising a pair of hubs adapted to be mounted in tandem relation upon said drive shafts, propeller blades adjustably carried by each of said hubs, the blades of one hub being of opposite pitch to those of the other hub, fluid pressure actuating means in each of said hubs for effecting adjustment of said blades to vary the pitch thereof, separate fluid pressure developing means in each hub to supply fluid under pressure to said actuating means within that hub, means within each hub for controlling the application of the fluid pressure to the actuating means of that hub to effect adjustment of the pitch setting of the blades thereof, independent means in one of said hubs for regulating the controlling means of that hub to adjust the setting of its said blades to a predetermined position, a member in said other hub responsive to the position of the blades of said first mentioned hub, a second member in said other hub responsive to the position of the blades of that hub, and means responsive to the position of said two members for regulating the action of the controlling means of said other hub to provide for maintaining a predetermined relation between the setting of the blades of said two hubs.

19. A dual rotation propeller of the character 

